Method of applying herbicidal imidates



United States Patent ABSTRACT OF THE DISCLOSURE Disclosed herein is a method of applying liquid herbicidal compounds of the formula R is alkyl of 1 to 6 carbon atoms,

R is phenyl, methylphenyl, mono, dior trichlorophenyl, methylchlorophenyl or alkoxyphenyl wherein the alkoxy group has up to 5 carbon atoms,

Z is methyl or chloro, and

Y is oxygen or sulfur.

wherein These compounds are sprayed in their undiluted liquid form onto a locus containing undesired plants wherein the spray comprises drops of a substantially uniform size up to about 500 microns in diameter.

This invention deals with a novel method for the application of herbicidal compounds. More particularly, this invention relates to the application of undiluted liquid herbicidal imidates of the formula R is alkyl of 1 to 6 carbon atoms,

R is phenyl, methylphenyl, mono-, dior trichlorophenyl,

methylchlorophenyl or alkoxyphenyl wherein the alkoxy group has up to 5 carbon atoms,

2 is methyl or chloro, and

Y is oxygen or sulfur.

Typically, R represents methyl, ethyl, propyl, isopropyl, butyl, 2-methylbutyl, sec-pentyl, 1,1-dimethylbutyl, hexyl or Z-methylpentyl.

Typically, R represents phenyl, 4-methylphenyl, 4- chlorophenyl, 3,4-dichlorophenyl, 2,4,5-trichlorophenyl, 2-methyl-4-chlorophenyl or 4-methoxyphenyl.

It is well known in the art that herbicides are generally applied to the desired plants in the form of granules, sprays or dusts. The active agent in said spray or solid formulation is usually a minor proportion of the total product applied, whereas the major proportion is made up of a carrier, such as water, inert organic solvent, solid or other agronomically suitable materials. Of course, this method of application results in substantial economic waste, that is, the carrier in which the herbicides are incorporated normally serves no valuable agricultural purpose other than providing a medium in which the herbicide may be deposited on the plant. Therefore, a great deal of material, that is, the carrier, is simply wasted. In addition, the expense involved in transporting and delivering the herbicidal mixtures to the plants is greatly increased because of the magnitude of the material involved. Where airplane application is contemplated, the volume and weight of the material to be applied is parwherein ticularly critical. Because of this criticality, there has been a constant search for methods in which the weight and bulk required to spray any particular acreage could be reduced. The present invention provides just such a breakthrough in the method of applying herbicides. Said invention provides for the first time a novel, low-volume method of herbicidal application while still obtaining very high herbicidal activity.

Recently, there has been a substantial amount of eX- perimentation with regard to the low-volume application of insecticides. The state of the art in this respect is evidenced by the following publications:

Agricultural Chemicals, pp. 6970, June 1965, Chemical Week, pp. 59 60, January 1965, Farm Technology, pp. 9-10, April 1965, and Mississippi Farmer, A New Method of Applying Insecticides, June 1963.

These publications describe in some detail the procedures and equipment used in the successful low volume application of malathion LV, a liquid insecticide produced by the American Cyanamid Company.

It is an object of this invention to provide a method of applying particular herbicidal compounds.

It is a further object of this invention to improve the herbicidal effectiveness of particular compounds.

Another object of this invention is the improvement of resistance to loss of herbicidal activity by rainfall after treatment.

Other objects of this invention will be evident upon further reading of this disclosure.

Typical liquid imidates which are particularly valuable for the control of weeds when applied by the method of this invention are:

Phenyl N- (3 ,4-dichlorophenyl propionimidate,

4-methoxyphenyl N- (3,4-dichlorophenyl propionimidate,

2,4,5 -trichlorophenyl N- (3,4-dichlorophenyl) propionimidate,

Phenyl N- (3 ,4dichl0rophenyl) isobutyrimidate,

Details of their preparation and herbicidal activity are disclosed in United States patent application Ser. No. 521,821, filed on even date herewith. Said compounds have exhibited excellent herbicidal activity when applied to plants in the normal or usual manner, that is, in a spray consisting of the above compounds in a sutiable formulation. However, surprising results were obtained when said compounds were applied to the plants in their undiluted liquid form. Whereas one might expect that the herbicidal activity would decrease under such conditions, on the contrary, the activity greatly increased. Not only did the undiluted compounds of the present invention surpass their own activity when applied in the normal diluted form, but they showed even better herbicidal activity than that of a well known commercial herbicide; namely, 3,4-dichloropropionanilide, which is described in British Patent No. 903,766.

The novel method of this invention involves the application of the compounds of Formula I to the plants to be treated.

Said compounds are applied neat or in their undiluted liquid form. For the sake of this invention, the terms undiluted, low volume and neat are used interchangeably to denote that the compound is in its natural or technical state as made in contradistinction to the compound being incorporated in one or more adjuvants. In addition to applying the compounds of Formula I to the plants in their undiluted liquid form, it is also necessary, in order to accomplish the objectives of this inventiOn, that such application consist of liquid drops of generally uniform size, in the range of up to about 500 microns in diameter. Reasonably uniform drops of about 100 to 300 microns are preferable.

The amount of the compound which will be herbicidally elfective when applied according to this invention will depend, of course, on the nature of the plants to be treated, the weather and other variables normally encountered in such operations. Generally, an application rate of about A to 10 pounds of herbicide per acre will prove to be satisfactory. The actual amount to be used can easily be determined by one skilled in the art.

The delivery system used in this invention can be either ground or air type. The only requisite of such system is that it be adaptable for applying the compounds of Formula I to plants in low volume and in drops of generally uniform size and within the stated range.

The herbicidal effectiveness of this unique method of application was demonstrated by the use of a standard method of comparison. Certain crops and weeds were grown in pots. After the seeds germinated and the seedlings developed, the resulting plants were treated with the various herbicides. The treatment took place about two weeks after the seeds were planted. The percent phytotoxicity or injury was observed at regular intervals thereafter and recorded. Table I details the results of these tests.

Imidates applied by the method of this invention may be considered as precursors of the herbicidally effective 3,4-disubstituted anilides. For this reason, typical imidates, such as phenyl N-(3,4-dichlorophenyl)propionimidate and 4-rnethoxyphenyl N- (3 ,4-dichlorophenyl propionimidate, were compared as disclosed in Tables I, II and III with 3,4-dichloropropionanilide on a basis of molar equivalency.

An observation of would indicate that there was no effect on the plant and an observation of 100% would indicate a complete kill of the particular plant in question. Of course, observations between 0 and 100% would indicate such proportional injury.

It should also be noted that in recent years there has been a growing tendency to use the term phytotoxicity only when referring to injury evident in agronomic crops and not in reference to weeds. Such terms as kill or control are more appropriately used when referring to the injury evident in weeds. Of course, the term injury may be used when dealing with either agronomic crops or weeds.

TABLE I Table I shows very clearly that the weed killing ability of the imidates is greatly increased when they are applied to the plants to be treated in their undiluted liquid state in the manner of this invention. As for example, at a level of 3 pounds per acre of phenyl N-(3,4-dichlorophenyl)propionimidate, there is recorded a 63% injury of barnyard grass after 14 days from the date of treatment using a normal high volume spray, that is, 50 gallons per acre. However, when the same compound is sprayed at the same dosage using the method of this invention, there is a 100% kill of barnyard grass after an equivalent lapse of time. These results are even more surprising when you consider the effect of the 3,4-dichloropropionanilide on the barnyard grass at a level of 3 pounds per acre. An injury of 87% after 14 days is obtained when this commercial herbicide is applied as a spray at the normal high volume level, whereas an injury of only 77% is obtained when the same compound is applied using the general method of this invention.

It is, of course, well known that the commercial herbicide, 3,4-dichloropropionanilide, is highly selective. For this reason, it proves extremely useful for weed control in rice since it does not injure the rice to any appreciable extent while killing the surrounding weeds. Similar crop selectivity is also evident in the various imidates used in this invention. Therefore, it is especially important that this selectivity not be changed as a result of the method of application. A standard test using rice was run by the method previously described. The data are presented in Table II.

TABLE 11 Percent pliytotoxicity of rice (On 2a satire) High volume I Low volume 2 Days after application Compound Lbs. lacre Phenyl N-(3,4-dichloropheny1)- propionimidate 23 43 13 3,4-dichloropropionanilide 1 Application by spraying of an acetone solution at the rate of 50 gallons per acre.

2 Application of the herbicide in its undiluted liquid state using equipment suitable for obtaining uniform drop size. In the case of the 3,4- dichloropropionanilide, a water emulsion made from a. commercial emulsifiable concentrate was sprayed at the rate of 10 gallons per acre using the same equipment.

3 Based on the molar equivalency of 3,4-dichloropropionanilide.

Percent Injury on Percent Injury on Barnyard Grass Flax (Echinochloa crusgalli) (Lmum usz'tatz'ssimum) High Low High Low Volume Volume Volume Volume Days After Application Days After Application Compound Lbs/acre 3 7 14 3 7 l4 3 7 14 3 7 14 Phenyl N-(3A-dichloro- 1.5 40 4O 40 i7 77 80 20 20 13 73 80 77 phenyl)propionimidatd- 3.0 50 G3 57 87 100 37 40 37 73 77 63 l 1 6.0 50 70 S0 70 70 60 73 U0 U0 4-1nothoXyp1eny N- 3,4- 31 5 50 60 6O 43 dichlorophenyl)propion- M iinidate 80 H 1. 7 73 3 5 3,4-d1chlo1op1op1onanilide 3'0 50 87 87 33 9O acre using the same equipment.

Based on the molar equivalency of 3,4-(1icliloropropionauihde.

at the same level of concentration using a normal high wherein volume spray, there is a 20% injury to rice after 14 days. R is alkyl of 1 to 6 carbon atoms, In both cases the rice recovers from the injury. This R is phenyl, methylphenyl, mono-, dior trichloroclearly shows that the method of this invention does not phenyl, methylchlorophenyl or alkoxyphenyl whereimpair the herbicidal selectivity of the imidates. 5 in the alkoxy group has up to 5 carbon atoms,

The novel method of application, disclosed hereinbe- Z is methyl or chloro, and fore, not only increases the herbicidal activity of the imi- Y is oxygen or sulfur, wherein said spray comprises dates of Formula I, but it also improves their resistance drops of substantially uniform size of up to about to reduction in such activity when the plants are sub- 500 microns in diameter. jected to rain shortly after treatment. The results detailed 2. A method according to claim 1 wherein the said in Table :III clearly sustain this conclusion. The data in 1 liquid imidate is phenyl N-(3,4-dichlorophenyl)propionsaid table were obtained by making observations at the imidate.

stated times after low volume treatment of the plants. 3. A method according to claim 1 wherein the said The crops and weeds used were grown in pots. After the liquid imidate is 4-methoxyphenyl N-(3,4-dichloroseeds germinated and the seedlings developed, the re- 5 phenyl)propionimidate.

sulting plants were treated, as stated in the table. This 4. A method according to claim 1 wherein the said treatment took place about two weeks after the seeds liquid imidate is applied at the rate of A to 10 pounds were planted. About 6 hours after the herbicide treatment, per acre.

the plants, other than the control group, were subjected 5. A method according to claim 1 wherein said spray to a two-inch simulated rain. Thereafter, the plants were 20 is applied by the use of an airplane.

observed and such observations were recorded as shown. 6. A method according to claim 1 wherein said spray TABLE III-EFFECT OF RAIN ON HERBIOIDAL ACTIVITY Percent Injury On- Crabgrass Barnyard Grass No Rain Rain No Rain Rain Days After Application Days After Application Compound Lbs./acre 3 7 14 3 7 14 3 7 14 3 7 14 PMNittdwhlowphayl)momma 4 as a .33 g2 a a a a 32 23 g; g; 4-methoxvphenv1N-awichlowphenrl)propionimidate &3 ::3:::::::::::::::::::::::': i? Z? 133 3% 3. 135 1. 5 50 63 33 30 30 20 3 37 30 3 10 3,4-diehloropropionanilide 3.0 53 80 77 30 37 17 17 67 77 0 23 20 6. 0 63 95 90 53 63 33 20 87 77 7 43 27 Percent Injury On- Flax Rice No Rain Rain No Rain Rain Days After Application Days After Application Compound Lbs/acre a 7 14 a 7 14 a 7 14 a 1 14 a Phenyl N-(3,4-d1ch1o op propwmmldfltfi 1 a i; i8 28 i3 22, ,8 4-methoxyphenyl N-(3,4-dich1or p y )p p 3 Q3 jjjjjjjj'jjj": $3 53 Z? Z? 1. 5 3 7 0 3 3 0 20 3O 17 20 20 3,441ichloropropionamhde 3 3. 0 10 23 7 10 13 3 10 27 17 2o 13 6. 0 30 33 20 13 27 3 1 Applied in undiluted liquid form with equipment suitable for obtain- 2 Applied at the rate of 10 gallons per acre with equipment suitable for ing uniform drop size (about 100 microns). obtaining uniform drop size (about 100 microns).

3 Based on the molar equivalency of 3,4-dichloropropionanilide. At a level of 1.5 pounds of phenyl N-(3,4-dichlorocomprises drops in the range of about 100 to 300 microns phenyl)propionimidate per acre, there was a 93% injury in diameter. of crabgrass (Digitaria sanguinalis) after 14 days where 7. A method according to claim 1 directed to the conthere was no exposure to rain. Those plants exposed to trol of barnyard grass. the rain showed an injury of 83% after the same length of 8. A method according to claim 1 directed to the contime. These results are to be compared with those obtrol of crabgrass. tained when the plants were treated with the commercial 9. A method according to claim 1 directed to the conherbicide, 3,4-dichloropropionanilide. At a level of 3 trol of weeds in rice. pounds per acre, there was an injury of 77% on the crabgrass after 14 days where the plants were not sub- References Cited jected to the rain. However, those plants subjected to the UNITED STATES PATENTS rain had an injury of only 17% after the same length of 2 909 553 V1959 h time. This is a clear showing that the low volume appli- Step ens 71*421 X cation of irnidates improves the abality to control weeds 3123460 3/1964 Schafer et 7198 X when they are subjected to a rain shortly after herbicidal 3180890 4/1965 Enders et a1 71 98 X f g fi' OTHER REFERENCES 1. A method of controlling plant growth which com- Ennis, 6f W V01 1, Pages 67 f0 prises spraying onto a locus, in which undesired plants 7 6 are growing, a herbicidally effective amount of an un- 7 diluted liquid imidate of the general formula LEWIS GOTTS, y EXaIIllIleI $1 CATHERINE L. MILLS, Assistant Examiner 

